The existing ladder comprises two stiles and at least a step mounted between the two stiles. The existing ladder generally comprises two structures below:
The first mounting structure, which utilizes a fastener directly fastens the stile and step, said supporting structure has drawbacks as follows: the shearing force generated between the step and stile is only supported by the fastener, so the fastener is easy to breakdown, its life length is relatively short and its safety performance is relatively low.
The second mounting structure, its stile is disposed with through hole, the end of step is embedded into the through hole and then be fastened, although said supporting structure is able to solve the drawbacks of the above mounting supporting structure, it has its own shortages: because the stile has to set through hole on it, so the strength of the stile would be eliminated. In order to enhance the strength of the stile, it has to enlarge the cross section of the stile or use a solid stile, which will greatly increase the quantity of material used and the manufacturing cost.